Flexible type circuit assemblies typically comprise a polymeric film, cloth, or other flexible substrate upon which a conductive ink, dye, or coating having a polymer matrix and conductive particles is applied to form a circuit member. These dyes, inks, and coatings are similar in nature in that they are dispersions of conductive particles in a polymer matrix and are applied first in a wet form and then cured by drying. These circuit assemblies are widely used due to their relatively low cost of production and flexible nature which allows them to be used in areas where traditional printed circuit boards can not be used such as in flexible connection circuits, Radio Frequency Identification (RFID) applications, particularly in clothing and low cost electronic components, and the like.
While such flexible printed circuit assemblies are relatively low in cost, they are not readily interconnected with and to other circuit assemblies, devices, and/or apparatuses. More particularly, such interconnections undesirably require crimping or the use of conductive adhesives or tapes, or relatively expensive separable mechanical connectors, each of which are relatively costly and produce substantially unreliable connections.
U.S. Pat. No. 7,211,205 issued to Conaghan, et al. describes using metal-coated tabs for soldering. This is an expensive and time consuming process.
U.S. Pat. No. 5,962,151 issued to Paszkiet, et al. describes forming a solderable deposition on a non solderable surface.
U.S. Pat. No. 7,144,830 issued to Hill, et al. describes attaching electrical components to woven fabric such as conductive yarn, for example, by connecting the components to the conductive yarn by soldering.
U.S. Pat. No. 7,224,280 issued to Ferguson et al. describes using electrically conductive adhesive.
European Patent Application EP 1039543 A2 to Morgan Adhesives Company comprises a thin substrate having two printed conductive ink pads. This method is said to be suitable for mass production of radio frequency identification tags (RFIDs) by mounting integrated circuits on interposers that are then physically and electrically connected to antenna sections using a pressure sensitive conductive adhesive.
U.S. Pat. No. 7,237,724 issued to Singleton describes a smart card and a method for manufacturing the same wherein the smart card is composed of a printed circuit board having a top surface and a bottom surface, a plurality of circuit components attached to the top surface of the printed circuit board, a filler board attached to the top surface of the printed circuit board, a bottom overlay attached to the bottom surface of the printed circuit board, a top overlay positioned above the top surface of the printed circuit board, and a thermosetting polymeric layer positioned between the top surface of the printed circuit board and the top overlay.
U.S. Pat. No. 6,381,482 issued to Jayaraman et al. uses conductive bumps that may be welded to the antenna by laser welding or ultrasonic welding.
U.S. Pat. No. 7,064,299 issued to Green et al. describes a flexible body that has a conductive resistance pathway which includes conductive resistance flexible strands of material connected in series between two supply bus flexible strands of material, and a temperature dependent variable resistance pathway with temperature dependent variable resistance flexible strands of material electrically connected in series by connection bus flexible strands of material.
U.S. Pat. No. 7,025,596 issued to Zollo et al. describes a method and apparatus for forming electrical connections between electronic circuits and conductive threads that are interwoven into textile material.
Each of the above references is incorporated herein by reference in its entirety.
Since it is expensive to form a connection from the methods described in the prior art, such as mechanical connectors and conductive adhesives, there is a necessity of an improved process to simplify the attachment process and make use of traditional bonding methods. Therefore, there is a need for a flexible type electrical circuit assembly which may be selectively, reliably, and cost effectively interconnected to another circuit assembly, device, or apparatus. Furthermore, there is a need for a method to produce such a circuit assembly that is easily connectable to other circuit components using traditional cost effective methods such as soldering or ultrasonic bonding. There is a further need for such flexible circuit assembly which may be used in a wide variety of applications such as printed electronic circuit connections to conventional printed circuit boards, battery terminals, battery current collector terminals, or to other electronic components such as push buttons or alarms using traditional soldering or ultrasonic bonding. A significant obstacle in achieving this is the inability of the current coatings, inks, or dyes to conduct the heat used to create the bond or to provide a surface that is capable of being bonded to. The heat from ultrasonic welding is the result of the friction used to bond the materials, and soldering utilizes the heat of the applied solder. Additionally, the surface of the ink, dye, or coating is bondable so that there can be a strong and thermally conductive surface that can accept the bond materials or be capable of being melted by the vibration at the interface of the two components. The dyes, inks, and coatings also should be formed from a simple wet dispersion of conductive particles in a polymer matrix that can be applied first in a wet form and then cured by drying so that the conductive material is easily applied and formed.